Si SiO 2 Si SiO 2 h si Si(100) “SOI” h si 5, 10, 20 nm Démouillage Film mince de SiNanostructures de Si Recuit (T>800 o C)

Présentation au sujet: "Si SiO 2 Si SiO 2 h si Si(100) “SOI” h si 5, 10, 20 nm Démouillage Film mince de SiNanostructures de Si Recuit (T>800 o C)"— Transcription de la présentation:

1 Si SiO 2 Si SiO 2 h si Si(100) “SOI” h si 5, 10, 20 nm Démouillage Film mince de SiNanostructures de Si Recuit (T>800 o C)

2 The end product: nanoislands are semi-organized (130) (100) (130) (150) (100) (150) (100) 10 μm

3 Surface energy driven kinetics of SOI dewetting LEEM / KMC Area (μm 2 ) t (s) LEEM Kinetic Monte Carlo simulations A (μm 2 ) t (arb. unit) Surface Energy driven SOS square lattice (3ML thick film) First neighbors interaction Substate/Film interaction Si(001) T=860°C H=21±2 nm Diffusion limited kinetics A~t 0.5 (Srolovitz et al. JAP, 1986) A~t 0.8 (Wong et al. Acta Mat., 2000) A~t (Pierre-Louis et al., PRL, 2009) Continuum models Nucleation on facet based model

4 Front velocity anisotropy versus local rim height Map of front position versus time (LEEM) Rim centers thicken and slow down (v ~ t -0.5 ) Void fingers exhibit constant velocity Rim height (AFM) 32±3 nm 29±3 nm Void fingers have constant rim height

5 Steady state dewetting of front The front velocity is stable and fingers are organized V front = 49±2 nm/s (T=900°C)

6 AFM versus KMC at the void finger tip AFMKMC Height (ML) x (atomic unit) x (μm) z (μm)

7 Finger void velocity model/experiment J=-D.grad (c) c eq,A > c eq,B Si film B A SiO 2 Receeding front J h L c eq,A ≈ c eq,B e E s /kTh DΩDΩ hL V finger ~ c eq,B (e -1) E s /kTh Top view Side view Void finger Receeding front Accumulated Si Si film A B Si rim E s : adsorbate-substrate excess energy 6nm h=21nm Danielson PhD (MIT, USA) 12nm 8nm 21 nm 6 nm

8 The thermal activation barrier to dewet Barrier surface smoothing on Si(100): E a =2.3±0.1 eV (T=800-1100 o C)* *M.E. Keeffe, J. Phys. Chem. Solids (1994) Void finger speed E a =2.0 ±0.2 eV Top view Void finger Receeding front Accumulated Si Si film A B Si rim c eq,A > c eq,B Si film B A SiO 2 Receeding front J h L Side view Void fingers E s : adsorbate-substrate excess energy E a : activation energy

9 Dynamics of solid state dewetting: straight fronts a model system for dewetting

10 - and - Si/SiO 2 straight fronts H=21 nm; T=804 o C (84.7 min) Stable front Unstable front 15 µm Cheynis et al., accepted PRB 2011 Lithography e - 500  m 60  m Atomic Force Microscopy 7  m -0.2 0 Z (  m) 5  m 0.18  m 1D profile LEEM Optical Microscopy (Plateforme Planete C’Nano PACA)

11 Stable front: evidence of a facetted rim in situ LEEM 15 µm SiO 2 Si rim Rim profile of stable front is facetted Si  =0.31±0.05 T=970°C T=825°C Rim displacement: x  t   =0.38±0.05 Experiment:  exp =0.35±0.05 Theory:  theory =7/22  0.32 Pierre-Louis et al. PRL 2009 Dufay et al. PRL 2011 Leroy et al. En preparation

12 Aire (μm 2 ) t (s) 0s1250s 4 µm

13 Aire (μm 2 ) t (arb. unit)

14 Height (ML) x (unité atomique) x (μm) z (μm)

15 c eq,A > c eq,B Film de Si B A SiO 2 Recul du front J h L Vue de dessus Void finger Recul du front Si accumulé Film de Si A B Bourrelet de Si Vue de côté

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17 Lithographie « Lift off » faisceau e - PMM A Si Si (wafer) SiO 2 Gravure du Si Microscopie Optique 500  m 60  m Microscopie à force atomique 7  m -0.2 0 Z (  m) 5  m 0.18  m 1D profile

18 4 µm trou carrédoigtnanostructure

19 140 µm 100 µm 670 µm 530 µm fronts Nucléation hétérogène Film de Si Tranchée Film de Si démouillé 24 min 0 min 5 µm Front stable Front instable

20 0204060 0 1 2 3 Déplacement du front (µm) temps (min)  =0.31±0.05 T=970°C T=825°C  =0.38±0.05 x t

21 15 µm SiO 2 Bourrelet de Si

22 0102030405060 0 100 200 Croissance (couche/couche) temps (min) 0 10 0 1 15 µm SiO 2 Bourrelet de Si

23 (1x2) (2x1) ∆t =0.36 min/monolayer ~ 22 s/monolayer ∆t (1x2) =26.1 s/monolayer ∆t (2x1) =17.4 s/monolayer ∆t (1x2) / ∆t (2x1) =1.5 Comportement moyen

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25 ex situ AFM (20  20 µm)  25s in situ LEEM Lateral Instability: new branch -0.1 µm 0.25 µm 2.5 µm

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